With the popularization of VR/AR, data centers, mobile devices, and CDNs, there will be more and more demand for network bandwidth in the future. People’s demand for network bandwidth is currently increasing geometrically, and with it comes the massive increase in high-bandwidth capacity Ethernet ports demanded by ultra-large-scale data centers and cloud vendors, such as 100GbE, 200GbE, 400GbE, and even future 800GbE . These high-bandwidth and capacity Ethernet ports help meet the growing east-west data traffic demand in the data center. At this time, a network switch and other network devices (such as servers or media converters) are needed for data transmission. , Hot-swappable network interface modules came into being. SFP, SFP+, SFP28, QSFP+ and QSFP28 are different types of optical transceivers, and when facing these different types of modules, such as SFP vs SFP+, SFP28 vs SFP+, QSFP vs QSFP28, what is the difference between them? You may often hear the question: Is QSFP28 compatible with QSFP+? Can I use the SFP28 transceiver on the SFP+ port? In this article, we will introduce these different types of modules and share these questions.
SFP(small form-factor pluggable)
SFP (small form-factor pluggable) is an upgraded version of GBIC (Gigabit interface converter). Its volume is only 1/2 of the GBIC module, which greatly increases the port density of network equipment. The data rate of SFP ranges from 100mbps to 4gbit/s.
SFP+ (small form-factor pluggable plus) is an enhanced version of SFP. It supports 8 Gbit/s Fibre Channel, 10 Gigabit Ethernet and optical transmission network standard OTU2. SFP+ also introduces direct connection to connect two SFP+ ports without the need for additional optical transceivers, including DAC (direct connection cable) and AOC (active optical cable), which is a short distance between two adjacent network switches. Very good solution for connectivity.
The main difference between SFP and SFP+:
1. SFP and SFP+ have the same appearance size;
2. The highest rate of SFP can reach 4G, and the rate of SFP+ is 10G;
3. SFP protocol specification: IEEE802.3, SFF-8472;
4. SFP+ supports digital diagnosis.
SFP28(small form-factor pluggable 28)
SFP28 (small form-factor pluggable 28) is an enhanced version of SFP+. SFP28 has the same common form as SFP+, but supports 25Gb/s on a single channel. SFP28 provides a new network upgrade method: 10G-25G-40G-100G, which is an energy-saving solution to meet the growing demand of next-generation data center networks. The current data center market is beginning to change from 10Gb/s Transition to 25Gb/s solution.
QSFP+(quad small form-factor pluggable)
QSFP+ is the evolution of QSFP (quad small form-factor pluggable). QSFP can carry 4 channels at the same time, and each channel can handle a data rate of 1Gbit/s, hence the name Quad SFP. Unlike QSFP, QSFP+ supports 4x 10 Gbit/s channels. These 4 channels can be combined into a 40 Gigabit Ethernet link. QSFP+ transceivers can replace 4 standard SFP+ transceivers, which have higher port density and overall system cost savings than traditional SFP+ products. QSFP28QSFP28 (quad small form-factor pluggable 28) is suitable for 100G applications. It provides 4 high-speed differential signal channels with data rates ranging from 25 Gbps to possible 40 Gbps, and finally meets the requirements of 100 Gbps Ethernet (4×25 Gbps) and 100 Gbps unlimited bandwidth enhanced data rate (EDR). Please note that QSFP28 can achieve 4x25G and 2x50G forked connections, or 1x100G connections, depending on the type of transceiver used
SFP vs SFP+:
The same size, different speed and compatibility SFP and SFP+ transceivers are almost the same in size and appearance. This allows equipment manufacturers to reuse existing SFP physical designs for network switches with SFP+ ports. As for the difference, the obvious point is that they support different transmission speeds, SFP up to 4 Gbit/s, while SFP+ is 10Gbit/s. In addition, they meet different specifications. SFP is based on the SFF-8472 protocol, and SFP+ complies with SFF-8431 and SFF-8432.
In terms of SFP and SFP+ compatibility, SFP+ ports usually accept SFP optics, but the speed is reduced by 1 Gbit/s. The SFP+ transceiver cannot be inserted into the SFP port, otherwise the product or port will be damaged.
SFP28 vs SFP+:
SFP28 is an upgraded version of SFP+. SFP28 has been upgraded to handle 25 Gbit/s per lane. They use the same form factor, and the pinouts of the SFP28 and SFP+ connectors are matched and compatible. So SFP28 will work with SFP+ optical system, but the speed will be reduced by 10 Gbit/s. If the SFP28 port of the SFP+ module can be set to 10G transmission, the SFP+ module can be used well with the SFP28 port on the network switch, otherwise the SFP+ module cannot work. In terms of copper cables, compared with the SFP+ version, SFP28 copper cables have greater bandwidth and lower loss.
SFP28 vs QSFP28:
Work according to different principles Although their names have a number "28", the SFP28 and QSFP28 transceivers actually use different sizes and working principles.
SFP28 only supports one 25Gbit/s channel, while QSFP28 supports 4 independent 25Gbit/s channels. Both of them can be used in 100G networks, but SFP28 is a disconnect cable applied to SFP28 in the form of QSFP28. The following shows the direct connection from 100G QSFP28 to 4x SFP28 DAC.
QSFP+ vs QSFP28:
Different speeds have different purposes. The QSFP+ and QSFP28 transceivers integrate 4 transmit and 4 receive channels with the same size. In addition, QSFP+ and QSFP28 product series both include transceiver modules and DAC/AOC cables, but the speeds are different. QSFP+ module supports 1x40gbit/s, QSFP+ DAC/AOC cable supports 4x10Gbit/s. The QSFP28 module can transmit 100 Gbit/s data, and the QSFP28 DAC/AOC cable can run at 4x 25 Gbit/s or 2x 50 Gbit/s. Please note that usually QSFP28 modules cannot be broken into 10G links. But inserting a QSFP+ module into the QSFP28 port is another situation, if the switch supports (how to implement 4x 10G mode on the QSFP28 100G port, please visit QSFP28 100G port to play 40G, 25G and 10G). In this case, QSFP28 can break through 4x10G like QSFP+ transceiver module.
The differences between SFP and SFP+, SFP28 and SFP+, QSFP+ and QSFP28 in different types of transceivers are clearly explained in this article. Although some of them share the same design, they are designed for different data rates. It can be seen from the comparison that the main driving force for the development of optical transceivers is the need to use a smaller form-factor to obtain a higher bandwidth rate. For example, in the same form-factor, QSFP28 provides more bandwidth than QSFP+.